The need for new anti-infective agents and strategies is underscored by recent acceleration in bacterial resistance to existing antibiotics and the exhaustion of currently known targets of microbial cell biology and biochemistry. Further anti-infectives development will be driven by discovery of the pathogenic molecular processes of infectious diseases, which are often initiated by host-pathogen encounters at epithelial surfaces. Urinary tract infections (UTIs), a major source of morbidity and medical costs worldwide, are caused primarily by uropathogenic Escherichia coli, which employ an adhesive fiber termed the type 1 pilus to bind and invade bladder epithelial cells. Recurrences are common after acute UTI, and recent data suggest that bacteria establish chronic residence within bladder tissue, resist oral antibiotic therapy, and re-emerge to cause these recurrences. In this application, we propose to deliver anti-infective agents into epithelial cells via the conjugation of antimicrobial-bearing polymer nanoparticles (NPs) with a bacterial adhesin, a protein that confers epithelial binding and invasion capacity upon our model Gram-negative pathogen. Our first objective will be to refine the chemical processes by which a subject protein (specifically the binding domain of the E. coli type 1 pilus adhesin FimH) can be conjugated with favorable orientation and distribution to the exterior of a series of polymer NPs. Second, we will demonstrate the adhesin-dependent internalization of these functionalized NPs into bladder epithelial cells in vitro and in vivo, providing uniquely available controls to prove the specificity of the adhesin-receptor interaction. Third, we will optimize the loading of silver cation and structurally modifiable silver carbene antimicrobials into the NPs. Finally, we propose to demonstrate the anti-infective activity of these antimicrobial-bearing, adhesin-coupled NPs, both in vitro and in murine models of acute and chronic cystitis caused by uropathogenic E. coli. Advantages of this system include the capability to deliver antimicrobials in high concentration to the intracellular compartment where pathogens may reside, avoidance of toxicities associated with systemic antibiotic and NP administration, and flexibility in the structural design of both the protein coat and the antimicrobial passenger. Though we will model the utility of our system using bacterial infection of the mammalian urinary tract, the delivery of pharmacologic agents of choice into selected epithelial cell populations will have broader applications spanning infectious diseases, cancer, and vaccine antigen delivery.